The present utility relates generally to a combined type intrusion and attack sensing means, more particularly to an intrusion and attack means which combine the sensing methods of microwave sensing and shock sensing.
The present burglarproof means generally adopts the microwave and the Doppler effect to sense an intrusion. As shown in FIG. 1, the conventional microwave sensing means employs a microwave antenna ANT to transmit a signal with frequency in the microwave band within a predetermined range. The signal will be reflected by any object moving within above range and the reflected wave will be received by the antenna ANT. The reflected wave subjected to the Doppler effect will be mixed with original signal to generate a difference-frequency signal. The difference-frequency signal is amplified by a band pass filter 2 to amplify the specific frequency range required. The amplified and filtered signal is sent to a comparator circuit for comparison with a reference threshold to generate a trigger signal to drive the alarm-generating circuit. The alarm-generating circuit will raise an alarm in case of intrusion. Alternatively, The attack of the burglar can be sensed by a shock sensing method. However, above two sensing means operate independently, and the intrusion and attack means with a function of combining microwave sensing and shock sensing is not yet available.
In view of above problems, the preset utility is intended to provide an intrusion and attack means which combine microwave sensing and shock sensing.